Differences

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--- pcbetching [2022-01-16 11:37] – [PCB Etching] jtdburton
+++ pcbetching [2022-01-18 21:04] – [Cutting] jtdburton
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 Sodium hydroxide ("drain cleaner"/photonegative stripper): Highly caustic. Wear gloves. Can be flushed down the drain (it's drain cleaner).
-Ferric chloride (etchant): Wear gloves. Wear eye protection. Touch it and die. Can be reused for months or even years, so you shouldn't need to dispose of it; if you do, there's a tub under the sink for the used stuff. DO NOT flush down the drain. DO NOT. You will kill hundreds of marine invertebrates who are just trying to have a nice day, and when the giant shrimp overlords arise, you will be their first sacrifice.
+Ferric chloride (etchant): Moderately corrosive, strong skin and eye irritant, toxic if consumed, toxic vapours. Wear gloves. Wear eye protection. Open a window and/or switch on the air filter. Can be reused for months or even years, so you shouldn't need to dispose of it; if you do, there's a tub under the sink for the used stuff. DO NOT flush down the drain.
 ===== Design/file prep =====
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 Use your image editing software of choice to prepare your cut file for lasering. It needs to be a vector with all shapes as outlines and no fill, and it needs to be mirrored either in your image editor or once you import it into the LaserCut software.
-Place your workpiece in the laser cutter copper side DOWN. Cut settings may need some experimenting to get right. The aim is to cut all the way through the substrate without hitting the copper hard enough to cause lots of sparks. My best results have come from using the big laser with speed 35, power 60, corner power 50 on 1.5mm board.
+Place your workpiece in the laser cutter copper side DOWN. Cut settings may need some experimenting to get right. The aim is to cut all the way through the substrate without hitting the copper hard enough to cause lots of sparks. My best results have come from using the big laser with speed 25, power 60, corner power 50 on 1.5mm board.
 Run the cuts. Give it a couple of minutes before you open the lid, vapourised FR1/2 isn't as bad as FR4 but it's still unpleasant.
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 ===== Exposure ====
+Grab the laminator, some sellotape, and a pair of scissors from G1 before you start with this section.
 Currently (as of January 2022) the lab has NEGATIVE photoresist, which means the copper will be removed from the areas of your board NOT exposed to UV light.
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 Cut a piece slightly larger than your board from the roll of photoresist film kept wrapped in a black bag in the cabinet in G14. PUT THE ROLL BACK IN THE BAG - it's UV sensitive.
-Peel off the backing (this is incredibly annoying to do - a couple of pieces of sellotape on either side of the corner can help peel the layers apart) and apply the blue film to your board. Try to squeeze any bubbles or wrinkles out to the sides, then run the board through the laminator in G1 to seal it. The laminator should be set on the largest thickness setting (2x125MIC), and it helps to run it through two or three times to improve the bond.
+Peel off the backing (this is incredibly annoying to do - a couple of pieces of sellotape on either side of the corner can help peel the layers apart) and apply the blue film to your board. Try to squeeze any bubbles or wrinkles out to the sides, then run the board through the laminator. The laminator should be set on the largest thickness setting (2x125MIC), and it helps to run it through two or three times to improve the bond.
 Put your mask and film-coated board together in a sort of deadly yet exciting chemical sandwich. Align as best you can using the mounting holes you hopefully punched out earlier, and add some sellotape to hold everything together.